Online language exams offer a convenient and accessible way to measure proficiency, but ensuring their reliability, validity and fairness requires robust security measures. This chapter explores the evolving landscape of online exam security and the importance of a multifaceted approach. Traditional cheating methods have adapted to the online environment, necessitating constant vigilance from exam security specialists. Standardised security protocols are crucial to maintain stakeholder confidence in test results. While no system is impregnable, multilayered defences throughout the exam cycle significantly deter cheating and uphold exam integrity. These defences encompass a range of measures to safeguard the exam at every stage. This multifaceted approach includes encryption protocols for the secure delivery of exam questions, standardised hardware and software requirements, limitations on background applications and Internet access, and various invigilation methods (live, recorded, or AI-powered). Identity verification techniques like biometric data analysis and environment scans confirm the test taker’s identity and prevent unauthorised assistance. Secure exam delivery is achieved through special browsers that restrict access to the exam webpage only, and secure note-taking provisions minimise the risk of compromising exam content. Finally, advanced security measures like AI-powered monitoring can detect suspicious behaviour, while plagiarism detection safeguards the overall integrity of the exam content. These are discussed based on language certification at-home exams like: IELTS Online, TOEFL iBT Home Edition, TOEFL Essentials, Pearson English International Certificate (PEIC), PTE Academic Online, LanguageCert International ESOL (IESOL), Duolingo English Test (DET) and Occupational English Test at-home version (OET@home).